1. Field of the Invention
The present invention relates to a transmission and reception method with multiple remote controllers where a single receiver can receive signals at the same frequency from multiple remote controllers using infrared, radio wave, or acoustic wave while identifying the individual remote controllers.
2. Description of the Related Art
Conventional remote controllers for remotely operated individual machines use carrier waves at different frequencies for transmitting signals. The receiver receives the signals transmitted from different remote controllers, and demodulates them independently to identify the signals transmitted from the individual remote controllers.
The conventional remote controller uses a transmission method in which an analog signal is sampled to produce a digital signal. A predetermined bit length of the digital signal is set as one frame of a transmission data. The transmission data is transmitted from the remote controller in a predetermined time interval.
This transmission and reception method for the remote controller does not have any specific problems as long as only a single remote controller is used with a corresponding the single receiver.
When multiple remote controllers attempt to simultaneously transmit instruction signals for different controls to the single receiver at the single location, because of the chance that output signals from the multiple remote controllers interfere with one another, it is necessary to avoid interference in this application form.
However, when the same type of remote controllers using the same carrier frequency and the same transmission interval for transmitting data are used simultaneously at the same location, the data transmitted from more than one of the multiple remote controllers may have the same timing. This can cause interference. Because received data overlap at the receiving units, the received data cannot be interpreted. As a result, the remote control is disabled.
The applicant has proposed “TRANSMISSION AND RECEPTION METHOD WITH MULTIPLE REMOTE CONTROLLERS” (Japanese Patent Laid-Open Publication No. Hei. 7-284174, referred to as Prior art 1 hereinafter) to solve these problems which discloses the following.
1. A transmission and reception method with multiple remote controllers comprising:
at least two remote controllers for transmitting transmission signals consisting of equal unit transmission periods (TT) for individual channels;
a single receiver for receiving said transmission signals;
wherein one period of a transmission period (ST) of said transmission signal consists of a transmission enabled period (STa) and a transmission disabled period (STb), these periods have a relationship of Sta≦STb; and
said unit transmission period (TT) consists of a data transmission period (DTa) and a data stop period (DTb), said transmission enabled period (STa) is set to said unit transmission period (TT)×2i−1 (where “I” is a positive integer, and is a unique number set to a proper number that is different from one channel to another), said data transmission period (DTa) and said data stop period (DTb) have a relationship of DTa≦DTb, and said transmission period (ST) is repeated for the transmission.
2. The transmission and reception method with multiple remote controllers according to claim 1, wherein said transmission enabled period (STa) and said transmission disabled period (STb) have a relationship of STa=STb.
3. The transmission and reception method with multiple remote controllers according to claim 1 or claim 2, wherein said data transmission period (DTa) and said data stop period (DTb) have a relationship of DTa=DTb.
4. The transmission and reception method with multiple remote controllers according to any one of claim 1 to claim 3, wherein a smallest possible number is selected first when said unique number “I” is assigned.
The unit transmission period (TT) of the transmission signals transmitted from the individual remote controllers 101A to 101D is equal among the individual channels in Prior art 1. The data transmission period (DTa) and the data stop period (DTb), of which the unit transmission period (TT) consists, have the relationship that the data transmission period (DTa)≦the data stop period (DTb).
Because states where the transmission signals from the individual remote controllers receive no interference from the other remote controllers are always generated within a predetermined period, while the transmission signals are assumed to cause interference state in Prior art 1, even if multiple remote controllers are used for a single receiver at the same frequency and at the same location, it is possible to transmit at the same frequency based on the same protocol.
The transmission period (ST) for transmitting signals from the individual channels, which consists of the transmission enabled period (STa), and the transmission disabled period (STb), is set such that the transmission enabled period (STa)≦the transmission disabled period (STb), an ith (“I” is a natural number) remote controller sets the number of the data transmission periods (DTa) to 2i−1 (“I” is a positive integer), and sets the transmission enabled period (STa) to the unit transmission period (TT)×2i−1 in Prior art 1.
When the transmission enabled period (STa) and the transmission disabled period (STb) is the same (STa=STb) in Prior art 1, for example, because the ith (“I” is a natural number) remote controller repeats the transmission period (ST) where the number of the data transmission periods (DTa) is set to 2i−1 (“I” is a positive integer), and the transmission enabled period is set to the unit transmission period (TT)×2i−1 as shown in FIG. 11, and the receiver of any one of channels receives the signal only from that channel during one transmission period (ST) for CH 5 whose “i” is the largest, the single receiver respectively receives the independent transmission signals for all channels at the same frequency based on the same protocol.
However, among the remote controllers having properly set “i” (“i” is a natural number) for the individual channels, a remote controller which has a larger “i” has the transmission enabled period (STa) for continuously transmitting a signal, and the transmission disabled period (STb) for stopping transmitting the signal longer than that for a remote controller with smaller “i” in the signal transmission in the prior art as shown in FIG. 11. For example, after the remote controller for CH 5 repeats to transmit the signals 16 times (part X), a period where the transmission is disabled continues for 16 unit transmission periods (TT) (part Y). When a button for commanding transmission is pressed in the transmission disabled period (STb) on the remote controller for CH 5, the transmission is disabled until the next transmission enabled period (Sta). This slows down the response of the receiver to the operation. Specifically, when five players use five remote controllers to play a video game, for example, there is a problem that when a player for CH5 instructs a transmission at X2 again immediately after the player instructs a transmission at X1, because X2 is in the transmission disabled period (STb) for the remote controller for CH 5, the commanded information is cancelled for the second time.
The purpose of the present invention is to provide a transmission and reception method with multiple remote controllers where a single receiver receives individual transmission signals at the same frequency based on the same protocol for all channels, and differences in the response time which occur among the individual channels are decreased.